A study was conducted to investigate the metapopulation structure of the tiger ( Panthera tigris ) in Nepal. The geographic distribution of tigers in Nepal is presented in relation to habitat quality and an inventory and monitoring system is described which can be applied across the entire range of the species. Using information from previous studies, interviews with local people, and digital thematic mapper satellite data, 4 tiger populations were identified. Three occurred primarily within the borders of Nepal, and a fourth was across the border in India. It was estimated that there were 153 breeding tigers in these 4 populations. In the Chitwan population, 77% of breeding tigers lived in 3 protected areas; the rest occupied national forests. Tigers in all 4 populations survived in isolated forest remnants of what was once a continuous subtropical forest zone lying south of the Himalayas. Within central Nepal the ratio of good- to poor- quality tiger habitat ranged from 16% to 86% across 7 forest districts. The 4 areas with the highest ratio of good-quality habitat (>54%) supported breeding populations, one area with a marginal ratio of good-quality habitat (46%) was used only occasionally, while the 2 areas with the lowest ratio of good- quality habitat ( less than 26%) were not used by tigers. It is suggested that when the ratio of good to poor habitat drops below approximately 50%, tigers no longer breed and when it drops below 30%, tigers no longer occur in an area. It is concluded that estimates of potential tiger habitat and data on habitat used by tigers demonstrated the need to expand current management beyond parks to encompass the entire land base supporting these fragmented populations so that small tiger populations can be managed as ecosystem or tiger management units rather than as portions of populations within protected areas.